1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
|
// Copyright 2015 The Emscripten Authors. All rights reserved.
// Emscripten is available under two separate licenses, the MIT license and the
// University of Illinois/NCSA Open Source License. Both these licenses can be
// found in the LICENSE file.
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <emscripten/emscripten.h>
#include <emscripten/threading.h>
#include <unistd.h> // usleep
#include <assert.h>
volatile int counter = 0; // Shared data
volatile int lock = 0; // spinlock "mutex" variable
void *ThreadMain(void *arg) {
printf("Thread started.\n");
for (int i = 0; i < 100; ++i) {
#ifdef USE_EMSCRIPTEN_INTRINSICS
while(emscripten_atomic_exchange_u32((void*)&lock, 1))
#else
while(__sync_lock_test_and_set(&lock, 1))
#endif
{
/*nop*/;
}
int c = counter;
usleep(5 * 1000); // Create contention on the lock.
++c;
counter = c;
#ifdef USE_EMSCRIPTEN_INTRINSICS
emscripten_atomic_store_u32((void*)&lock, 0);
#else
__sync_lock_release(&lock);
#endif
}
printf("Thread done.\n");
pthread_exit(0);
}
#define NUM_THREADS 8
int main() {
pthread_t thread[NUM_THREADS];
for (int i = 0; i < NUM_THREADS; ++i) {
int rc = pthread_create(&thread[i], NULL, ThreadMain, 0);
if (rc != 0 || thread[i] == 0) {
printf("Failed to create thread!\n");
}
}
for (int i = 0; i < NUM_THREADS; ++i) {
int rc = pthread_join(thread[i], 0);
assert(rc == 0);
}
printf("counter: %d\n", counter);
assert(counter == 800);
return 0;
}
|
